Underframe stress relief means



Nov. 28, 1967 J. C. TRAVILLA ET Al- UNDEEERAME sTREss RELIEF MEANS 2Sheets-Sheet;

Filed Aug.

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PUnited States Patent O W 3,354,840 UNDERFRAME STRESS RELIEF MEANS JamesC. Travilla, Ladue, and John R. Vogel, Northwoods, Mo., assignors toGeneral Steel Industries Inc., Granite City, lll., a corporation ofDelaware Filed Aug. 5, 1965, Ser. No. 477,564 4 Claims. (Cl. 105 420)ABSTRACT F THE DISCLOSURE `without reducing the clear height of thecenter plate boss.

The invention relates to railway rolling stock and consists particularlyin an improved underframe structure for cars having floating draftsills.

In cars of this type, to permit the positioning and free longitudinalmovement of the draft sill within the underframe center sill, it isnecessary that the interior of the latter be unobstructed throughout thelength of the car. This require-ment creates special problems at thecenter plate locations, where the body bolsters intersect the centersill. The body bolster is essentially a transverse beam loaded at itsends by the car side walls and supported at its midpoint by the cartruck. In conventional cars of the fixed center sill type, one or morevertical webs extend transversely through the center sill at the bolsterlocation to provide resistance to the high vertical bending moments inthis region and to reinforce the bottom web of the bolster, which formsits compression member under vertical loading.

The absence of any vertical webs across the center sill is complicatedby the further fact that the center plate, formed by a circular boss inthe bottom wa-ll of the bolster, normally intersects the horizontalportion of the bottom wall substantially at right angles, the latterbeing required to avoid interference with the upst-anding circular rimof the truck center plate. In view of the fact that the bottom wall ofthe bolster must function as the compression member of the bolster,serious stress concentrations `are encountered at the right angleintersections at the sides of the center plate, becoming less criticalfore and aft of .the center plate. Such stress concentrations tend tocause region. A further object is to provide such a construction inwhich the stress concentrations at both sides of the center plate aresubstantially reduced.

The foregoing and additional more detailed objects and advantages willIbe achieved by the construction described hereinafter and illustratedin the accompanying drawings,

in which:

FIG. 1 is a longitudinal vertical sectional view, along longitudinalcenter line 1 1 of FIG. 3 of an underframe end casting embodying theinvention, in its normal service position.

FIG. 2 is a transverse vertical sectional view along the bolster centerline 2 2 `of FIG.v 3.

3,354,840 Patented Nov. 28, 1967 FIG. 3 is a bottom view of the castingillustrated in FIGS. 1 and 2 taken from line 3 3 of FIG. 2.

FIG. 4 is an enlarged fragmentary bottom view showing the center plateregion of the casting.

FIGS. 5-8 are enlarged fragmentary vertical sectional views of thecenter plate portion of the bottom wall in normal service positioncorresponding to FIGS. 1 and 2, taken along lines 5 5, 6 6, 7 7 and 8 8,respectively, of FIG. 4.

FIGS. 9 and l0 are enlarged fragmentary vertical sectional views,corresponding to FIG. 5, 'of modified forms of the invention.

The underframe includes an end structure, preferably of cast metal andcruciform in plan, comprising an outer relatively long center sillportion 1, an inner relatively short center sill portion 3 arranged forattachment to an end of an intermediate center sill (not shown), andidentical body bolster arms 5, 5 intersecting center sill 1, 3 betweenits outer and inner portions 1 and 3.

The center sill .1, 3 is an inverted outwardly flanged channelcomprising a flat top wall 7, and spaced, longitudinally extendingvertical side walls 9 outwardly horizontally flanged along their lowermargins as at 11. The body bolster arms 5, 5 are of box section, eachcomprising a substantially horizontal top wall 13 merging with centersill top wall 7, vertical side walls 1'5 spaced apart lengthwise of thestructure and arcuately merging at their inner ends with the verticalside walls 9, 9 of center sill 1, 3, and a bottom wall 17, into whichcenter sill flanges 11 merge. Intermediate their ends, each of thebolster arms is formed with a downwardly facing side bearing 14, and thebolster arms also include full height internal central ribs 16 mergingat their inner ends with center sill side walls 9 and extendingoutwardly therefrom well past side bearings 14. To additionally tie theside bearings into the bolster side walls 15, additional ribs 18 extendthe full width of the bolster up from the bottom Wall over the sidebearings. Additional strength is imparted to the connection between thebolster arms and center sill by pairs of short ribs 20 extendingoutwardly from center sill side walls 9 and disposed on both sides ofbolster center web 16 and in spaced relation thereto.y

VThe intermediate por-tion 19 of bottom Wall 1-7 extends across thecenter sill and is formed with a depending hollow .cylindrical boss orbody center plate having an upright cylindrical side wall 21 and? a atbottom wall 23.

Center plate'21, y23` is arranged for mating pivotal engagement, as .amale part, with a female part formed by an upstanding -rim R on the topof a truck bolster. Rims R are -of standard height, to permitinterchangeability from car to car, and the height of the bottom surfaceof bottom wall central portion 19 is fixed by other factors whichseverely l-imit the height of upright cylindrical wall 21 to a dimensionjust sufficient to provide clearance between the top of rim R and thebottom of bottom Wall 19.

To reduce the stress concentration at the sides off center plate 21, 23,which would occur if the center pl-ate upright Wall 21 intersectedbottom wall 19 at a right angle or on a negligible radius at the sides,a large radius intersection is provided at Ithe sides by forming agroove 2S of generally crescent shape in plan partly in the bottom Wall19 and partly in the upright cylindrical wall 21 on both sides of thecenter plate, groove 25 being arcuate in vertical cross section ofsuticient radius to provide the desired reduction in stressconcentration. This maximum radius, shown in FIG. 5, is provided throughan arc extending approximately 20 on both 4sides of the transversecenter line as best seen in FIG. 4, the radius and depth of the recessgradually diminishing through' the next 25 until the recess terminatesand the minimum radius is 'reached at about 45 on each side of thetransverse center lin'e,

the latter obtaining along the generally transverse margins of thecenter plate between the grooves at each side.

As seen in FIGS. 5-8, this arrangement provides a la-rge radiusintersection between the horizontal bottom wall portion 19 and uprightcylindrical wall 21 at both sides of the center plate, and by beingrecessed into the two walls it does Anot interfere with the clearancerequired for the truck center plate rim R.

Additional strength is provided across the center sill by the provisionon the bottom of wall 19 of spaced pairs of continuous transverse ribsadjacent the forward and rear margins of bottom wall 19 and by pairs ofdiscontinuous ribs 29 disposed slightly inwardly, longitudinally of thesill of center plate cylindrical wall 21 and extending transverselyinwardly from their outer ends, which are substantially aligned with theouter ends of ribs 27, and then c urved in spaced relation with themargins of center plate wall 21 toward the adjacent rib 27 transverselyoutwardly from the margin of recesses 25, after which they merge intobottom wall 19 a short distance from ribs ,27. Further strength issupplied across the center plate by a transverse diametral rib 31 whollywithin the center plate depression in wall 19, while additional strengthis supplied to the sill across the center plate by a longitudinallyextending narrow box section member comprising bolster bottom w-all 19,center plate bottom wall 23, spaced longitudinally extending verticalside walls 33 and top wall 35.

In the embodiment illustrated in FIG. 9, stress relief is 'accomplishedby a large radius arcuate groove 37, wholly disposed in bolster bottomwall 19' and tangent tothe outer side surfaces of the cylindrical wall21'.

4In the embodiment illustrated in FIG. l0, the arcuate groove 39 iswholly disposed in the cylindrical wall 21" and is tangent tothe bottomsurface of bottom wall 19".

As in the first disclosed embodiment of the invention, grooves 37 and 39are formed at the sides only of the center plate, i.e., in the quadrantsbisected by the transverse diameter of the center plate and are of themaximum depth and radius throughout the same are as in the firstembodiment, i.e., approximately 20 on both sides of the transversediameter gradually diminishing thererfrom in depth and radius to anegligible radius through- `out the quadrants bisected by thelongitudinal diameter of the center plate.

The details of the structure may be modied substantially withoutdeparting from the spirit of the invention, and the exclusive use ofsuch modifications as come within the scope of the appended claims iscontemplated.

What is claimed is:

1. Underf-rame structure for a railroad car comprising a transverse beamunderlyingly Isupported at its center and vertically vloaded at itsends, said beam having spaced V,top land bottom walls `formingrespectively its tension and compression members, the central portion ofsaid bottom wall comprising a depending vertically disposed cylindricalboss and ya horizontal wall portion surrounding said `boss andperpendicularly intersecting the same, said boss forming a pivot centerplate for supporting said underframe on a swivel truck, there beinggrooves of arcuate cross section formed in said wall structure along theyintersection between said boss and said horizontal wall portion in theinterior angle thereof, said grooves being elongated lengthwise of thecar and serving to eliminate angular intersections transversely of saidbeam between said horizontal wall portions and said boss Withontinterfering with the pivot function of said boss, said grooves being-formed only `at the sides of said cylindrical bossi, the arcuate crosssection of said grooves being of substantially greater radius than thatof the ungrooved portions of the intersection of said horizontal Wallwith said cylindrical boss, each said groove contour being of maximumradius an equal distance on both sides of the transverse diameter ofsaid cylindrical boss, the radius and ,depth of each said groovegradually diminishing at;

both sides of said maximum radius region until each said groovedisappears and the radius becomes a constant minimum value through equaldistances on both sides of the longitudinal diameter of said cylindricalboss.

2. Underframe structure for a railroad car comprising a transverse beamunderlyingly supported at its center and vertically loaded at its ends,said beam having spaced top and bottom walls `forming respectively itstension and compression members, the centr-al portion of said bottomwall comprising a depending vertically disposed cylindrical boss and ahorizontal wall portion surrounding said boss and perpendicularlyintersecting the same, said boss forming a pivot center plate forsupporting said underframe on a swivel truck, there being grooves ofarcuate cross section formed in said wall structure along theintersection between said boss and said horizontal wall portion in theinterior angle thereof, said grooves being elongated lengthwise of thecar and serving to eliminate angular intersections transversely of saidbeam between said horizontal wall portions and said boss witho-utinterfering with the pivot function of said boss, said grooves beingformed only at the sides of said cylindrical boss, the arcuate crosssection of said grooves being of substantially greater radius than thatof the ungrooved portions of the intersection of said horizontal wallwith said cylindrical boss, said grooves being formed wholly within saidhorizontal wall and each said groove contour is of maximum radius anequal distance on both sides of the transverse diameter of saidcylindrical boss, the radius and depth of each said groove graduallydiminishing at both sides of said maximum radius region until each saidgroove disappears and the radius becomes a constant minimum valuethrough equal distances on both sides of the longitudinal diameter ofsaid cylindrical boss.

3. Underframe structure for a railroad car comprising a transverse beamunderlyingly supported at its center and vertically loaded at its ends,said beam having spaced top and bottom walls forming respectively itstension and compression members, the central portion of said bottom wallcomprising a depending vertically disposed cylindrical boss and ahorizontal wall portion'surrounding said boss and perpendicularlyintersecting the same, said boss forming ya pivot center plate forsupporting said underframe on a swivel truck, there being ygrooves ofarcuate cross section formed in s aid Vwall structure lalong theintersection between said boss and said horizontal wall portion in theinterior angle thereof, said grooves being elongated lengthwise of `thecar and serving to eliminate angular intersections transversely of saidbeam between said horizontal wall portions and s-aid boss withoutinterfering with the pivot function of said boss, said groovesv beingformed only at the sides of said cylindrical boss, the arcuate crosssection of said grooves being lof substantially greater radius than thatof the ungrooved portions of the intersection of said horizontal wallwith said cylindrical boss, said groove being formed wholly within theouter surface of said cylindrical boss andeach s-aid groove contour isof maximum radius an equal distance on both sides of the transversediameter of said cylindrical boss, the radius and depth of each saidgroove gradually diminishing `at both sides of said maximum radiusregion until each said groove disappears and the radius becomes aconstant minimum value through equal distances on both -sides of ,thelongitudinal diameter of said cylindrical boss.

4. Underframe structure for a railroad car comprising a transverse beamunderlyingly supported at itsY center and vertically loaded at its ends,said beam having spaced top and bottom Walls forming respectively itstension and compression members, the central portion of said bottom Wallcomprising a depending vertically disposed cylindrical boss and ahorizontal wall portion surrounding said boss and perpendicularlyintersecting the same, said boss forming -a pivot center plate forsupporting said Unfit-Timm@ @Il a Swivel -truck there being grooves ofarcuate cross section formed in said wall structure along theintersection between said boss and said horizontal wall portion in theinterior angle thereof, said grooves being elongated lengthwise of theoar and serving to eliminate angular intersections transversely of saidbeam between said horizontal Wall portions and said boss withoutinterfering with the pivot function of said boss, said grooves beingformed only at the sides of said cylindrical boss, the arcuate crosssection of said grooves being of substantially greater Iradius than thatof the ungrooved portions of the intersection of said horizontal Wallwith said cylindrical boss, each of s-aid grooves being formed partlyWithin both said horizontal wall and the exterior of said cylindricalboss and each said groove contour being of maximum radius an equaldistance on both sides of the transverse diameter of said cylindricalboss, the radius and depth of each said groove gradually diminishing atboth sides of said maximum radius region until each said groovedisappears and the radius becomes a constant minimum value through equaldistances on both sides of the longitudinal diameter of said cylindricalboss.

References Cited ARTHUR L. LA POINT, Primary Examiner. DRAYTON E.HOFFMAN, Examiner.

1. UNDERFRAME STRUCTURE FOR A RAILROAD CAR COMPRISING A TRANSVERSE BEAMUNDERLYINGLY SUPPORTED AT ITS CENTER AND VERTICALLY LOADED AT ITS ENDS,SAID BEAM HAVING SPACED TOP AND BOTTOM WALLS FORMING RESPECTIVELY ITSTENSION AND COMPRESSION MEMBERS, THE CENTRAL PORTION OF SAID BOTTOM WALLCOMPRISING A DEPENDING VERTICALLY DISPOSED CYLINDRICAL BOSS AND AHORIZONTAL WALL PORTION SURROUNDING SAID BOSS AND PERPENDICULARLYINTERSECTING THE SAME, SAID BOSS FORMING A PIVOT CENTER PLATE FORSUPPORTING SAID UNDERFRAME ON A SWIVEL TRUCK, THERE BEING GROOVES OFARCUATE CROSS SECTION FORMED IN SAID WALL STRUCTURE ALONG THEINTERSECTION BETWEEN SAID BOSS AND SAID HORIZONTAL WALL PORTION IN THEINTERIOR ANGLE THEREOF, SAID GROOVES BEING ELONGATED LENGTHWISE OF THECAR AND SERVING TO ELIMINATE ANGULAR INTERSECTIONS TRANSVERSELY OF SAIDBEAM BETWEEN SAID HORIZONTAL WALL PORTIONS AND SAID BOSS WITHOUTINTERFERING WITH THE PIVOT FUNCTION OF SAID BOSS, SAID GROOVES BEINGFORMED ONLY AT THE SIDES OF SAID CYLINDRICAL BOSS, THE ARCUATE CROSSSECTION OF SAID GROOVES BEING OF SUBSTANTIALLY GREATER RADIUS THAN THATOF THE UNGROOVED PORTIONS OF THE INTERSECTION OF SAID HORIZONTAL WALLWITH SAID CYLINDRICAL BOSS, EACH SAID GROOVE CONTOUR BEING OF MAXIMUMRADIUS AN EQUAL DISTANCE ON BOTH SIDES OF THE TRANSVERSE DIAMETER OFSAID CYLINDRICAL BOSS, THE RADIUS AND DEPTH OF EACH SAID GROOVEGRADUALLY DIMINISHING AT BOTH SIDES OF SAID MAXIMUM RADIUS REGION UNTILEACH SAID GROOVE DISAPPEARS AND THE RADIUS BECOMES A CONSTANT MINIMUMVALUE THROUGH EQUAL DISTANCES ON BOTH SIDES OF THE LONGITUDINAL DIAMETEROF SAID CYLINDRICAL BOSS.